Viruses trojans spyware

In contrast to viruses, which require the spreading of an infected host file, worms are standalone software and do not require a host program or human help to propagate. To spread, worms either exploit a vulnerability on the target system or use some kind of social engineering to trick users into executing them. A worm enters a computer through a vulnerability in the system and takes advantage of file-transport or information-transport features on the system, allowing it to travel unaided.

More advanced worms leverage encryption, wipers, and ransomware technologies to harm their targets. A Trojan is another type of malware named after the wooden horse that the Greeks used to infiltrate Troy. It is a harmful piece of software that looks legitimate. Users are typically tricked into loading and executing it on their systems. After it is activated, it can achieve any number of attacks on the host, from irritating the user popping up windows or changing desktops to damaging the host deleting files, stealing data, or activating and spreading other malware, such as viruses.

Trojans are also known to create backdoors to give malicious users access to the system. Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self-replicate. Trojans must spread through user interaction such as opening an email attachment or downloading and running a file from the Internet. Bots often automate tasks and provide information or services that would otherwise be conducted by a human being.

They may also be used to interact dynamically with websites. Bots can be used for either good or malicious intent. In addition to the worm-like ability to self-propagate, bots can include the ability to log keystrokes, gather passwords, capture and analyze packets, gather financial information, launch Denial of Service DOS Attacks , relay spam, and open backdoors on the infected host. Bots have all the advantages of worms, but are generally much more versatile in their infection vector and are often modified within hours of publication of a new exploit.

They have been known to exploit backdoors opened by worms and viruses, which allows them to access networks that have good perimeter control.

Bots rarely announce their presence with high scan rates that damage network infrastructure; instead, they infect networks in a way that escapes immediate notice. Advanced botnets may take advantage of common internet of things IOT devices such as home electronics or appliances to increase automated attacks.

Crypto mining is a common use of these bots for nefarious purposes. Advanced malware typically comes via the following distribution channels to a computer or network:. A set of stealthy and continuous computer hacking processes, often orchestrated by a person or persons targeting a specific entity. An APT usually targets either private organizations, states, or both for business or political motives. APT processes require a high degree of covertness over a long period of time. The "advanced" process signifies sophisticated techniques using malware to exploit vulnerabilities in systems.

The "persistent" process suggests that an external command and control system is continuously monitoring and extracting data from a specific target. The "threat" process indicates human involvement in orchestrating the attack. Software that generates revenue for its developer by automatically generating online advertisements in the user interface of the software or on a screen presented to the user during the installation process. The software may generate two types of revenue: one is for the display of the advertisement and another on a "pay-per-click" basis if the user clicks on the advertisement.

An undocumented way of accessing a system, bypassing the normal authentication mechanisms. Some backdoors are placed in the software by the original programmer and others are placed on systems through a system compromise, such as a virus or worm. Usually, attackers use backdoors for easier and continued access to a system after it has been compromised. Adversaries may use bootkits to persist on systems at a layer below the operating system, which may make it difficult to perform full remediation unless an organization suspects one was used and can act accordingly.

Software that modifies a web browser's settings without a user's permission to inject unwanted advertising into the user's browser. A browser hijacker may replace the existing home page, error page, or search engine with its own. These are generally used to force hits to a particular website, increasing its advertising revenue. This software often comes in the form of a browser toolbar and is received through an email attachment or file download.

A class of malware designed specifically to automate cybercrime. Crimeware distinct from spyware and adware is designed to perpetrate identity theft through social engineering or technical stealth in order to access a computer user's financial and retail accounts for the purpose of taking funds from those accounts or completing unauthorized transactions that enrich the cyberthief. Alternatively, crimeware may steal confidential or sensitive corporate information.

Malicious attempts by one or more people to cause the victim, site, or node to deny service to its customers. A computer file that contains a sequence of instructions to run an automatic task when the user clicks the file icon or when it is launched via a command. For more general tips, see prevent malware infection. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info.

Contents Exit focus mode. Is this page helpful? A dropper is often the first stage in a multi-phase trojan attack, followed by the installation of another type of trojan that provides attackers with a persistent foothold in an internal system. For example, a dropper can be used to inject a backdoor trojan into a sensitive server.

It may allow hackers to control the device, monitor or steal data, and deploy other software. Spyware is software that observes user activities, collecting sensitive data like account credentials or banking details. They send this data back to the attacker. Spyware is typically disguised as useful software, so it is generally considered as a type of trojan. Rootkit trojans acquire root-level or administrative access to a machine, and boots together with the operating system, or even before the operating system.

This makes them very difficult to detect and remove. Following are some of the fastest-spreading and most dangerous trojan families. It is estimated to have infected over 3. It is particularly effective at stealing credentials, banking details and other financial information and transmit them to the attackers.

Later versions of Zeus added a domain generation algorithm GDA , which lets Zbots connect to a list of alternative domain names if the Zeus server is not available. Recipients who were curious enough to open the attachment became infected, the trojan would overwrite files on the machine and then send itself to their entire contact list. This simple but effective propagation method caused the virus to spread to millions of computers.

Cryptolocker is a common form of ransomware. It distributes itself using infected email attachments; a common message contains an infected password-protected ZIP file, with the password contained in the message. It searches for files to encrypt on local drives and mapped network drives, and encrypts the files using asymmetric encryption with or bit keys.

The attackers then demand a ransom to release the files. The virus caused operator monitors to show business as usual, while it changed the speed of Iranian centrifuges, causing them to spin too long and too quickly, and destroying the equipment. Trojans are a major threat to organizational systems and a tool commonly used as part of Advanced Persistent Threats APT.

Security teams can use the following technologies and methods to detect and prevent trojans:. Modern endpoint protection systems include device traditional antivirus, next-generation antivirus NGAV that can prevent zero-day and unknown trojans, and behavioral analytics that identifies anomalous activity on user devices.